The objectives of the Registry of Experimental Cancers are 1) The storage and retrieval of pathologic material and data on cancers and other lesions of laboratory animals (primarily rodents) and 2) the use of such information for research and educational purposes. The Registry has acquired a total of 2129 (150 since the 1981 report) single or group accessions from investigators outside the NCI. Approximately 57,800 (2800 since the 1981 report) records have been coded. Thirty investigators have come to the Registry for study and consultation on single or multiple visits. One foreign investigator was a guest at the Registry for 2 months.